Next time Republicans have a House majority, they’ll have the power to baselessly politically persecute any current or former official through impeachment, and I expect they will since they can’t begin to grasp the fact Trump actually committed impeachable offenses.
But good luck regaining the trust of average Americans with loose talk like that.
And no you can’t impeach someone for crimes not committed pursuant to a public office; that’s the entire purpose of impeachment (not that I’m agreeing with you that Obama committed any crimes whatsoever before or after his presidency).